Blank for unbreakable watch crystals



Nov. 10, 1931. M. c. CAMPBELL 1,331,703

I BLANK FOR UNBREAKABLE WATCH CRYSTALS Filed Dec.- 5, 1927 Patented Nov. 10, 1931 UNITED STATES PATENT OFFICE MILTON C. CAMPBELL, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, T0 IRA GUILDEN, OF NEW YORK, N. Y.

BLANK FOR UNBREAKAIBLE WATCH CRYSTALS Application filed December 5, 1927. Serial No. 237,724.

This invention relates to blanks for unbreakable Watch crystals and its object is to provide a suitably domed blank from which a crystal ready for use can be easily cut.

And another object is to provide a suitably domed blank for unbreakable watch crystals which is adapted to be easily and quickly registered in a machine whereby the crystal may be cut from the blank with its margin symmetrically disposed in a predetermined manner about the dome for engagement with a bezel.

In Letters Patent 1,757,952 patented to me May 13, 1930, I have disclosed a machine which may be used for cutting a crystal from a blank of this invention.

In the accompanying drawings I have shown a selected embodiment of the invention and referring thereto,

Fig. 1 is a plan view of a blank.

Fig. 2 is a sectional View on the line 22 of Fig.

Fig; 3 is a sectional view on the line 83 of Fig. 1.

Fig. 4 shows the blank after the crystal has been cut out, and

Fig. 5 shows the crystal.

The blank 6 is made of celluloid or other suitable transparent material, it is conveniently made rectangular in shape, and it is provided centrally with a dome 7 of suitable size and shape. The blank may be of standard size to fit a cutting machine but the dome will vary in size and shape for crystals to fit different watches.

Two openings 8 are provided in the blank of a size and shape to receive snugly a pair of holding pins on the machine whereby the blank is properly centered for the cutting tool. These openings are preferably located diametrically opposite each other adjacent the edges of the blank and equi-distant from the dome so that the dome of the crystal will be centrally located within a relatively flat margin 9 to engage the bezel of the watch.

In Fig. 1 I have indicated by a broken line 10 where the blank should be cut to produce the crystal 11, Fig. 5, which leaves an openin 12 in the blank.

Illanks of uniform size and shape having domes of different sizes and shapes can be made and sold separately or in sets for use by jewelers, watch repairers and others for qiuckly making unbreakable crystals as required and in exactshape to fit any watch. These crystals are particularly desirable for bracelet watches which vary greatly in size and shape and my invention provides a means whereby they can be quickly cut to exact fit.

I have shown the invention in a simple form but it will he understood that the dome may be differently shaped and vary in size as may be found desirable, and other changes may be made without departing from the invention within the scope of the following claim.

I claim:

As an article of manufacture a blank prepared for cutting a watch crystal therefrom in a single final operation, comprising a flat piece of celluloid having a central portion upset from the plane of the piece to form a watch crystal and pilot openings in said piece beyond the crystal forming upset portion.

MILTON C. CAMPBELL. 

